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25
Closure and Convergence: A Foundation of FaultTolerant Computing
 IEEE Transactions on Software Engineering
, 1993
"... We give a formal definition of what it means for a system to "tolerate" a class of "faults". The definition consists of two conditions: One, if a fault occurs when the system state is within a set of "legal" states, the resulting state is within some larger set and, if faults continue occurring, the ..."
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Cited by 110 (30 self)
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We give a formal definition of what it means for a system to "tolerate" a class of "faults". The definition consists of two conditions: One, if a fault occurs when the system state is within a set of "legal" states, the resulting state is within some larger set and, if faults continue occurring, the system state remains within that larger set (Closure). And two, if faults stop occurring, the system eventually reaches a state within the legal set (Convergence). We demonstrate the applicability of our definition for specifying and verifying the faulttolerance properties of a variety of digital and computer systems. Further, using the definition, we obtain a simple classification of faulttolerant systems and discuss methods for their systematic design. as traditionally been studied in the context of specifi...
Resource bounds for self stabilizing message driven protocols
 Proc. of the Tenth Annual ACM Symposium on Principles of Distributed Computation
, 1991
"... Abstract. Selfstabilizing message driven protocols are defined and discussed. The class weakexclusion that contains many natural tasks such as ℓexclusion and tokenpassing is defined, and it is shown that in any execution of any selfstabilizing protocol for a task in this class, the configuration ..."
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Cited by 37 (10 self)
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Abstract. Selfstabilizing message driven protocols are defined and discussed. The class weakexclusion that contains many natural tasks such as ℓexclusion and tokenpassing is defined, and it is shown that in any execution of any selfstabilizing protocol for a task in this class, the configuration size must grow at least in a logarithmic rate. This last lower bound is valid even if the system is supported by a timeout mechanism that prevents communication deadlocks. Then we present three selfstabilizing message driven protocols for tokenpassing. The rate of growth of configuration size for all three protocols matches the aforementioned lower bound. Our protocols are presented for two processor systems but can be easily adapted to rings of arbitrary size. Our results have an interesting interpretation in terms of automata theory.
Kendall Square Multiprocessor: Early Experiences and Performance
 of the Intel Paragon, ORNL/TM12194
, 1994
"... Initial performance results and early experiences are reported for the Kendall Square Research multiprocessor. The basic architecture of the sharedmemory multiprocessor is described, and computational and I/O performance is measured for both serial and parallel programs. Experiences in porting vari ..."
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Cited by 21 (0 self)
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Initial performance results and early experiences are reported for the Kendall Square Research multiprocessor. The basic architecture of the sharedmemory multiprocessor is described, and computational and I/O performance is measured for both serial and parallel programs. Experiences in porting various applications are described.  v  1. Introduction In September of 1991, a Kendall Square Research (KSR) multiprocessor was installed at Oak Ridge National Laboratory (ORNL). This report describes the results of this initial field test. The performance of the KSR sharedmemory multiprocessor is compared with other sharedmemory and distributedmemory multiprocessors, using synthetic benchmarks and real applications. Performance figures must be considered preliminary, since the KSR system was in its first field test. The KSR multiprocessor runs a modified version of OSF/1 (Mach). To the user, the KSR system appears like typical UNIX TM , but providing performance advantages similar to...
Optimal Maintenance of Replicated Information
 In Proc. 31st IEEE Symp. on Foundations of Computer Science
, 1993
"... Those who cannot remember the past, are condemned to repeat it." (Philosopher George Santayana) In this paper we show that keeping track of history enables significant improvements in the communication complexity of dynamic networks protocols. We improve the communication complexity for solving ..."
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Cited by 14 (8 self)
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Those who cannot remember the past, are condemned to repeat it." (Philosopher George Santayana) In this paper we show that keeping track of history enables significant improvements in the communication complexity of dynamic networks protocols. We improve the communication complexity for solving any graph problem from \Theta(E) to \Theta(V ), thus achieving the lower bound. Moreover, O(V ) is also our amortized complexity of solving any function (not only graph functions) defined on the local inputs of the nodes. This proves, for the first time, that amortized communication complexity, i.e. incremental cost of adapting to a single topology change, can be smaller than the communication complexity of solving the problem from scratch. This also has a practical importance: in real networks the topology and the local inputs of the nodes change.
A SelfStabilizing Leader Election Algorithm for Tree Graphs
 Journal of Parallel and Distributed Computing
, 1996
"... We propose a self stabilizing algorithm (protocol) for leader election in a tree graph. We show the correctness of the proposed algorithm by using a new technique involving induction. 1 Introduction In a distributed system the computing elements or nodes exchange information only by message passing. ..."
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Cited by 14 (2 self)
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We propose a self stabilizing algorithm (protocol) for leader election in a tree graph. We show the correctness of the proposed algorithm by using a new technique involving induction. 1 Introduction In a distributed system the computing elements or nodes exchange information only by message passing. Every node has a set of local variables whose contents specify the local state of the node. The state of the entire system, called the global state, is the union of the local states of all the nodes in the system. Each node is allowed to have only a partial view of the global state, and this depends on the connectivity of the system and the propagation delay of different messages. Yet, the objective in a distributed system is to arrive at a desirable global final state (legitimate state), defined by some invariance relation on the global state. Systems that reach the legitimate state starting from any arbitrary (possibly illegitimate) state in a finite number of steps are called selfstabil...
Coupling and SelfStabilization
 DISTRIBUTED COMPUTING
"... A randomized selfstabilizing algorithm A is an algorithm that, whatever the initial configuration is, reaches a set L of legal configurations in finite time with probability 1. The proof of convergence towards L is generally done by exhibiting a potential function ϕ, which measures the “vertical ..."
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Cited by 13 (5 self)
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A randomized selfstabilizing algorithm A is an algorithm that, whatever the initial configuration is, reaches a set L of legal configurations in finite time with probability 1. The proof of convergence towards L is generally done by exhibiting a potential function ϕ, which measures the “vertical ” distance of any configuration to L, such that ϕ decreases with nonnull probability at each step of A. We propose here a method, based on the notion of coupling, which makes use of a “horizontal” distance δ between any pair of configurations, such that δ decreases in expectation at each step of A. In contrast with classical methods, our coupling method does not require the knowledge of L. In addition to the proof of convergence, the method allows us to assess the convergence rate according to two different measures. Proofs produced by the method are often simpler or give better upper bounds than their classical counterparts, as examplified here on Herman’s mutual exclusion and Iterated Prisoner’s Dilemma algorithms in the case of cyclic graphs.
Resource Bounds for SelfStabilizing MessageDriven Protocols
, 1997
"... Selfstabilizing message driven protocols are defined and discussed. The class weakexclusion that contains many natural tasks such as `exclusion and tokenpassing is defined, and it is shown that in any execution of any selfstabilizing protocol for a task in this class, the configuration size ..."
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Cited by 13 (1 self)
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Selfstabilizing message driven protocols are defined and discussed. The class weakexclusion that contains many natural tasks such as `exclusion and tokenpassing is defined, and it is shown that in any execution of any selfstabilizing protocol for a task in this class, the configuration size must grow at least in a logarithmic rate. This last lower bound is valid even if the system is supported by a timeout mechanism that prevents communication deadlocks. Then we present three selfstabilizing message driven protocols for tokenpassing. The rate of growth of configuration size for all three protocols matches the aforementioned lower bound. Our protocols are presented for two processor systems but can be easily adapted to rings of arbitrary size. Our results have an interesting interpretation in terms of automata theory.
Distributed Computing on the Move: From mobile Computing To Cooperative . . .
, 2001
"... Distributed computing is beginning to extend its scope to address problems relevant to a mobile environment (mobile computing). For the most part, current research e#orts in mobile computing and ad hoc networking are implicitly aimed at mobile telephony and the emerging field of ubiquitous computing ..."
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Cited by 12 (1 self)
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Distributed computing is beginning to extend its scope to address problems relevant to a mobile environment (mobile computing). For the most part, current research e#orts in mobile computing and ad hoc networking are implicitly aimed at mobile telephony and the emerging field of ubiquitous computing. More generally,
Efficient Selfstabilizing Algorithms for Tree Networks
, 2003
"... Many proposed selfstabilizing algorithms require an exponential number of moves before stabilizing on a global solution, including some rooting algorithms for tree networks [1, 2, 3]. These results are vastly improved upon in [6] with tree rooting algorithms that require only O(n³ + n² &m ..."
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Cited by 11 (1 self)
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Many proposed selfstabilizing algorithms require an exponential number of moves before stabilizing on a global solution, including some rooting algorithms for tree networks [1, 2, 3]. These results are vastly improved upon in [6] with tree rooting algorithms that require only O(n³ + n² · c_h) moves, where n is the number of nodes in the network and c_h is the highest initial value of a variable. In the current paper, we describe a new set of tree rooting algorithms that brings the complexity down to O(n²) moves. This not only reduces the first term by an order of magnitude, but also reduces the second term by an unbounded factor. We further show a generic mapping that can be used to instantiate an efficient selfstabilizing tree algorithm from any traditional sequential tree algorithm that makes a single bottomup pass through a rooted tree. The new generic mapping improves on the complexity of the technique presented in [8].